Field of Invention
The present invention relates to a chip package and fabrication method thereof.
Description of Related Art
The finger print sensor and the RF (radio frequency) sensor require the use of a flat sensing surface to detect a signal, and the detecting accuracy of these sensing devices is reduced if the sensing surface is not flat. For example, a finger is pressed against the sensing surface of the finger print sensor. If the sensing surface is not flat, it will be difficult to detect complete fingerprint.
In addition, a through silicon via (TSV) is formed in a wafer to expose a pad from the TSV in the fabrication of the above sensing devices. Then, a chemical vapor deposition (CVD) process is applied to form an isolation layer on the pad and on the sidewalls of the TSV. After that, a patterning process is applied to form an opening in the isolation layer to expose the pad. Generally, the patterning process includes exposing, developing and etching processes. In the subsequent process, a redistribution layer is formed on the isolation layer and electrically connected to the pad exposed by the opening of the isolation layer.
However, the CVD and patterning processes are required to spend a lot process time and machine costs.